The Impact Of Training on the  Hormones Of Special Operations Soldiers With Possible Applications to Tactical LE

Some interesting research going on at locals such as Natick Army Labs looking at the effects of
Stress, training, lack of sleep, and or reduced calories and their effects on hormones.

After identifying which hormones take a nose dive in response to high levels of stress, etc and which are correlated to performance, there may be an effort to alter/maintain those hormones which could allow SOF/Tactical LE to extend/improve their performance operationally speaking. Nutritional interventions are being examined (some of which I covered in my articles here) as well as other possible interventions that could be of considerable benefit to members of the military and law enforcement community, specifically – but not limited to – SOF and Tactical LE.

Brink Bottom Line: The intensity, volume, and type of exercise people do can have profound effects on their hormones. Additionally, total calories, macro nutrients, micro nutrients, and other dietary variables, such as total protein, can also effect hormones. Add to that high levels of stress, and other factors unique to soldiers and LE, and it’s clear hormonal changes – which can negatively impact performance, health, and operational longevity – are a given. Recent research aims to see which hormones, under what conditions, etc, and how they may impact the war fighter, whith possible applications to other groups, such as tactical LE. Clearly, focusing on good nutritional practices, the possible use of specific supplements, avoiding over training/OTS, managing stress, and other variables, can go a long way to avoiding these issues. However, it’s not always possible for soldiers, and to a lesser degree tactical LE, to adequately address the issues, so other interventions need to be considered and researched.

One hormone that seems to be of particular interest is IGF-1, which “… is a biomarker that may have greater utility than other conventional biomarkers in assessing nutritional, health, and fitness status” of SOF soldiers.”

A few study abstracts of interest:

J Appl Physiol. 2007 Apr 5;


* Nindl BC,
* Alemany JA,
* Kellogg MD,
* Rood J,
* Allison SA,
* Young AJ,
* Montain SJ.

Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States.

IGF-I is a biomarker that may have greater utility than other conventional biomarkers in assessing nutritional, health, and fitness status. We hypothesized the IGF-I system would directionally track a short-term energy deficit and would be more related to changes in body composition than other nutritional biomarkers. 35 healthy men (24+/-0.3 y) underwent 8 days of exercise and energy imbalance. Total and free IGF-I, IGFBP-1, – 2 and -3, the acid labile subunit (ALS), transferrin, ferritin, retinol binding protein (RBP), prealbumin, testosterone, T3, T4, leptin and changes in body composition were measured. Repeated measures ANOVA, correlation analysis and receiver operator characteristic (ROC) curves were used for statistical analyses (p </= 0 .05). Results: Body mass (-3.8 %), fat-free mass (-2.2%), and fat mass (- 12.9%) all decreased. Total and free IGF-I, IGFBP-3 and the ALS and prealbumin, but not transferrin, RBP and ferritin directionally tracked the energy deficit and losses in body composition. The correlation (r = 0.43) between changes in free IGF-I and body and fat-free mass was the only significant association observed. ROC curve analysis revealed that a baseline value < 1.67 for the molar volume ratio of IGF-I/ALS had an AUC of 0.745 and was a significant discriminator for those subjects losing >5 % body mass.

Conclusions: IGF-I is an important adjunct in the overall assessment of adaptation to stress imposed by pysical activity superimposed upon energy and sleep restriction and is more closely associated with losses in body mass and fat-free mass than other conventional nutritional biomarkers. Key words: Somatotrophic hormones, military operational stress, nutritional biomarkers, Soldier.
J Appl Physiol. 2003 Sep;95(3):1083-9.

Differential responses of IGF-I molecular complexes to military operational field training.

* Nindl BC,
* Castellani JW,
* Young AJ,
* Patton JF,
* Khosravi MJ,
* Diamandi A,
* Montain SJ.

Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA. Bradley.Nindl@NA.AMEDD.Army.Mil

Insulin-like growth factor (IGF) I and IGF binding proteins (IGFBPs) modulate metabolic activity and tissue repair and are influenced by nutritional status. IGF-I circulates in free, ternary [IGF-I + IGFBP-3 + acid labile subunit (ALS)], and binary (IGF-I + IGFBP) molecular complexes, and the relative proportions regulate IGF-I extravascular shifting and bioavailability. This study examined the hypothesis that sustained physical activity and sleep deprivation superimposed on a short-term energy deficit would alter the IGFBP concentrations and alter the proportions of IGF-I circulating in ternary vs. binary molecular complexes. Components of the IGF-I system (total and free IGF-I; IGFBP-1, -3, and ALS; nonternary IGF-I and IGFBP-3), biomarkers of metabolic and nutritional status (transferrin, ferritin, prealbumin, glucose, free fatty acids, glycerol, beta-hydroxybutyrate), and body composition were measured in 12 men (22 +/- 3 yr, 87 +/- 8 kg, 183 +/- 7 cm, 20 +/- 5% body fat) on days 1, 3, and 4 during a control and experimental (Exp) period. During Exp, subjects performed prolonged work (energy expenditure of approximately 4500 kcal/day) with caloric (1600 kcal/day) and sleep (6.2 h total) restriction. IGF-I and IGFBP-3 were measured by immunoassay before and after immunoaffinity depletion of ALS-based complexes (i.e., ternary complex removal). Exp produced losses in body mass (-3.0%), lowered total IGF-I (-24%), free IGF-I (-42%), IGFBP-3 (-6%), nonternary IGF-I (-27%), and IGFBP-3 (-16%), and increased IGFBP-1 (256%). No Exp effects were observed for ALS. No changes were observed in the proportion of IGF-I circulating in free ( approximately 1.2%), ternary ( approximately 87.4%), or nonternary ( approximately 11.4%) molecular complexes. During Exp, glucose concentrations were lower on day 3, but days 1 and 4 were statistically similar.

In conclusion, during a short-term energy deficit in young, healthy men, 1). IGF-I system components differentially respond (both in direction and magnitude) to a given metabolic perturbation and 2). the relative proportion of IGF-I sequestered in ternary vs. nonternary molecular complexes appears to be well maintained.

: Horm Metab Res. 2004 Jul;36(7):506-11.

Influence of energy deficiency on the insulin-like growth factor I axis in a military training program.

* Gomez-Merino D,
* Chennaoui M,
* Drogou C,
* Guezennec CY.

Department of Physiology, IMASSA-CERMA, 91223 Bretigny-sur-Orge, France.

The aim of this study was to determine wether continuous heavy physical activities as well as lack of food and sleep during military training (three weeks of conditioning followed by a five-day combat course) alter serum concentrations of IGF-I and/or its binding proteins, evaluating the relationship to metabolic changes. Before and after training, we measured serum levels of both total and free IGF-I, IGFBP-1 and IGFBP-3 as well as plasma levels of branched-chain amino acids (valine, leucine and isoleucine) and glucose from 26 cadets (21 +/- 2 yr). Total and free IGF-I levels were decreased after training from 228 +/- 12 to 160 +/- 7 ng/ml and from 0.80 +/- 0.08 to 0.52 +/- 0.06 ng/ml, p < 0.001 respectively) as well as IGFBP-3 (p < 0.001), while IGFBP-1 levels were increased (p < 0.001). BCAA levels were decreased from 245.4 +/- 7.5 to 215.9 +/- 5.1 micromol/l, p < 0.001, while those of glucose remained unchanged. There were correlations between changes in total IGF-I and IGFBP-3 (p < 0.05) and between free IGF-I and IGFBP-1 (p < 0.01). Several correlations appeared between changes in all the components of the IGF-I axis and branched-chain amino acids.

We concluded that responses of the IGF-I system during an intense training could represent an adaptative response to the encountered energy deficiency, resulting a diversion of substrate from growth to acute metabolic needs.


Medicine & Science in Sports & Exercise. 39(8):1380-1387, August 2007.


Purpose: Soldiers are expected to maintain a high degree of physical readiness as operational demands can severely degrade performance capabilities. This study examined the physiological consequences of U.S. Army Ranger training on strength, power, body composition, and somatotrophic hormones.
Methods: In an intensive 8-wk military training course that included an average daily energy deficit of 1000 kcal[middle dot]d-1, lower-body power output, maximal lifting strength, body composition, and serum concentrations of several somatotrophic hormones were measured in 50 male soldiers (24.6 +/- 4.4 y; 176.1 +/- 7.8 cm; 78.4 +/- 8.7 kg; 14.7 +/- 4.2% body fat) before and after the course.
Results: Vertical jump height (-16%), explosive power output (-21%), maximal lifting strength. (-20%), body mass (-13%), fat-free mass (-6%), and fat mass (-50%) declined (P < 0.05) after the training course. Circulating total testosterone and insulin-like growth factor-I (IGF-I) experienced significant (P < 0.05) declines, and cortisol was significantly increased. Lower-body power output, but not maximal lifting strength, correlated with changes in fat-free mass. IGF-I and cortisol, but not total testosterone, were correlated with losses of tissue mass.

Conclusion: Lower-body power output, estimated from vertical jump height and body mass, is a sensitive and field expedient measure that can be used to assess the influence of caloric deficit on physical performance after 8 wk of U.S. Army Ranger training. With severe weight loss (>=13% of body mass), IGF-I and cortisol correlate more closely with soft-tissue tissue adaptations than does testosterone. (C)2007The American College of Sports Medicine

  1. Rob McElhenney 9 years ago

    What’s your quick take on the potential benefit of various combinations of adaptogens for these special populations? Rhodiola Rosea often gets touted as a stress buster and something that tends to potentiate other adaptogens taken with it, so this seems like another simple avenue that may be of benefit to soldiers and law enforcement put in inordinately stressful situations.

    • Author
      Will Brink 9 years ago

      Rob, I don’t think there’s enough good data to recommend the herbal adaptogens to such populations at this time. Might be worth looking into for the military (and they might be…) but more research is clearly needed. User feedback on Rhodiola Rosea is generally good, but that’s more from the general fitness/bbing population.

  2. makster 9 years ago

    Great info Will. It’s nice to see that they are looking into keeping our soldiers and LEO’s in good condition. Both mentally and physically, to keep them at their best.
    Do you think this has any relation to the strss factors on the average bbing person? I know you said above that herbal adaptogens may not.

    • Author
      Will Brink 9 years ago

      Mak, there’s always some relation to the average person, and everything applies. I stress avoiding OTS all the time on the forums, the ebooks, here on the site, etc. Soldiers, more specifically SOF, don’t are under a different set of circumstances, and often have no choices in terms of taking a few extra days off, etc to avoid OTS, and such.

  3. fairlane 9 years ago

    Why bother with soldiers? They will be obsolete very soon 😉

    • Author
      Will Brink 9 years ago

      DARPA looks into some interesting stuff for sure. Robotics is part of the future no doubt. They have also developed a suit, that the soldier wears, that augments their strength. That’s being tested now. Wild stuff.

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